Buggy code:
public class InMemoryExpressionFactory implements ExpressionFactory { private static final Value NULL = new Null ( ) ; private static final Value CURRENT_DATE = new CurrentDate ( ) ; private static final Object UNIQUE = new Object ( ) ; private List _unbounds = null ; public boolean matches ( QueryExpressions exps , ClassMetaData type , boolean subs , Object candidate , StoreContext ctx , Object [ ] params ) { } private boolean matches ( Exp exp , Object candidate , StoreContext ctx , Object [ ] params , int i ) { } public List group ( QueryExpressions exps , List matches , StoreContext ctx , Object [ ] params ) { } public boolean matches ( QueryExpressions exps , Collection group , StoreContext ctx , Object [ ] params ) { } private boolean matches ( Exp exp , Collection group , StoreContext ctx , Object [ ] params , int i ) { } public List project ( QueryExpressions exps , List matches , StoreContext ctx , Object [ ] params ) { if ( ( exps . projections . length ) == 0 ) return matches ; <START_BUG> if ( ( ( exps . grouping . length ) == 0 ) && ( exps . aggregate ) ) { <END_BUG> Object [ ] projection = project ( matches , exps , true , ctx , params ) ; return Arrays . asList ( new Object [ ] { projection } ) ; } List projected = new ArrayList ( matches . size ( ) ) ; for ( Iterator itr = matches . iterator ( ) ; itr . hasNext ( ) ; ) projected . add ( project ( itr . next ( ) , exps , ( ( exps . grouping . length ) > 0 ) , ctx , params ) ) ; return projected ; } private Object [ ] project ( Object candidate , QueryExpressions exps , boolean agg , StoreContext ctx , Object [ ] params ) { } public List order ( QueryExpressions exps , List matches , StoreContext ctx , Object [ ] params ) { } private List order ( QueryExpressions exps , Value [ ] orderValues , boolean projected , List matches , StoreContext ctx , Object [ ] params ) { } public List distinct ( QueryExpressions exps , boolean fromExtent , List matches ) { } public Expression emptyExpression ( ) { } public Expression asExpression ( Value v ) { } public Expression equal ( Value v1 , Value v2 ) { } public Expression notEqual ( Value v1 , Value v2 ) { } public Expression lessThan ( Value v1 , Value v2 ) { } public Expression greaterThan ( Value v1 , Value v2 ) { } public Expression lessThanEqual ( Value v1 , Value v2 ) { } public Expression greaterThanEqual ( Value v1 , Value v2 ) { } public Expression isEmpty ( Value v1 ) { } public Expression isNotEmpty ( Value v1 ) { } public Expression contains ( Value v1 , Value v2 ) { } public Expression containsKey ( Value v1 , Value v2 ) { } public Expression containsValue ( Value v1 , Value v2 ) { } public Expression isInstance ( Value v1 , Class c ) { } public Expression and ( Expression exp1 , Expression exp2 ) { } public Expression or ( Expression exp1 , Expression exp2 ) { } public Expression not ( Expression exp ) { } public Expression bindVariable ( Value var , Value val ) { } public Expression bindKeyVariable ( Value var , Value val ) { } public Expression bindValueVariable ( Value var , Value val ) { } public Expression endsWith ( Value v1 , Value v2 ) { } public Expression matches ( Value v1 , Value v2 , String single , String multi , String esc ) { } public Expression notMatches ( Value v1 , Value v2 , String single , String multi , String esc ) { } public Expression startsWith ( Value v1 , Value v2 ) { } public Subquery newSubquery ( ClassMetaData candidate , boolean subs , String alias ) { } public Path newPath ( ) { } public Path newPath ( Value val ) { } public Literal newLiteral ( Object val , int parseType ) { } public Value getThis ( ) { } public Value getNull ( ) { } public Value getCurrentDate ( ) { } public Value getCurrentTime ( ) { } public Value getCurrentTimestamp ( ) { } public Parameter newParameter ( String name , Class type ) { } public Value newExtension ( FilterListener listener , Value target , Value arg ) { } public Value newAggregate ( AggregateListener listener , Value arg ) { } public Arguments newArgumentList ( Value val1 , Value val2 ) { } public Value newUnboundVariable ( String name , Class type ) { } public Value newBoundVariable ( String name , Class type ) { } public Value cast ( Value val , Class cls ) { } public Value add ( Value val1 , Value val2 ) { } public Value subtract ( Value val1 , Value val2 ) { } public Value multiply ( Value val1 , Value val2 ) { } public Value divide ( Value val1 , Value val2 ) { } public Value mod ( Value val1 , Value val2 ) { } public Value abs ( Value val ) { } public Value indexOf ( Value val1 , Value val2 ) { } public Value concat ( Value val1 , Value val2 ) { } public Value stringLength ( Value str ) { } public Value trim ( Value str , Value trimChar , Boolean where ) { } public Value sqrt ( Value val ) { } public Value substring ( Value val1 , Value val2 ) { }

Fix:
if ( ( ( exps . grouping . length ) == 0 ) && ( exps . isAggregate ( ) ) ) {